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Commit d572929c authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Jeremy Fitzhardinge
Browse files

paravirt: helper to disable all IO space 



In a virtual environment, device drivers such as legacy IDE will waste
quite a lot of time probing for their devices which will never appear.
This helper function allows a paravirt implementation to lay claim to
the whole iomem and ioport space, thereby disabling all device drivers
trying to claim IO resources.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarChris Wright <chrisw@sous-sol.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
parent 5f4352fb

arch/i386/kernel/paravirt.c

+35 −0
Original line number Diff line number Diff line
@@ -228,6 +228,41 @@ static int __init print_banner(void) 
}

core_initcall(print_banner);



static struct resource reserve_ioports = {

	.start = 0,

	.end = IO_SPACE_LIMIT,

	.name = "paravirt-ioport",

	.flags = IORESOURCE_IO | IORESOURCE_BUSY,

};



static struct resource reserve_iomem = {

	.start = 0,

	.end = -1,

	.name = "paravirt-iomem",

	.flags = IORESOURCE_MEM | IORESOURCE_BUSY,

};



/*

 * Reserve the whole legacy IO space to prevent any legacy drivers

 * from wasting time probing for their hardware.  This is a fairly

 * brute-force approach to disabling all non-virtual drivers.

 *

 * Note that this must be called very early to have any effect.

 */

int paravirt_disable_iospace(void)

{

	int ret;



	ret = request_resource(&ioport_resource, &reserve_ioports);

	if (ret == 0) {

		ret = request_resource(&iomem_resource, &reserve_iomem);

		if (ret)

			release_resource(&reserve_ioports);

	}



	return ret;

}



struct paravirt_ops paravirt_ops = {

	.name = "bare hardware",

	.paravirt_enabled = 0,

include/asm-i386/paravirt.h

+1 −0
Original line number Diff line number Diff line
@@ -262,6 +262,7 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *site, unsigned len) 
unsigned paravirt_patch_insns(void *site, unsigned len,

			      const char *start, const char *end);



int paravirt_disable_iospace(void);



/*

 * This generates an indirect call based on the operation type number.